How could Moses write that he himself was "the
most humble person on the face of the earth?" (Numbers 12:3)
Isn't that itself a contradiction to being truly humble?

Dear Robert Samuels,

Your question reminds me of a story: When the practice
of ritual slaughter was under attack in Great Britain, the famed
Rabbi Yechezkel Abramsky was called to court in its defense.

The judge read from the deposition which lay before him:
"Rabbi
Abramsky," said the judge, "it says here that you are
the foremost authority of Jewish Law in the British Empire. Is
that true?"

"That is true, your honor."

"And that you are the most eloquent spokesman
for Jewish Law in the British Empire?"

"That is also true, your honor."

"It also says here that you are the most senior
rabbi in the British Empire. Is that correct?"

"That is correct, your Honor."

Taken aback by the Rabbi's straight-forward responses,
the judge said, "Rabbi Abramsky, how do you resolve your
answers with the Talmudic teachings of humility?"

"It is indeed a problem, your honor,"
said the Rabbi. "But I'm under oath."

Moses was commanded by G-d to write that he was
the most humble person, so he had no choice but to write it.

Knowing your own greatness is no contradiction to
humility. On the contrary, ultimate humility is achieved by a
person who excels in good attributes but takes no credit for his
greatness. He realizes that all his achievements come from G-d,
and therefore he isn't conceited or self-congratulatory.